John –
Depending on how high up you get, most of the Southern Appalachians have a small yellow stonefly called the Little Yellow Sally. Especially for high altitude brook trout, bring Stimulators in size #10 and #12 with a lot of yellow in their bodies. It wouldn’t hurt to also bring a foam variant; you’re going to want to drop these right in the foam and curl of whatever micro-rapids you see; the brookies like to sit under that. But that turmoil can soak a fly quickly, so you’ll want to pinch them dry, flick them dry, and replace them a lot. Foam is good for that.
Zach